LUCA lived 4.2B years ago

[partinobodycular]

Does alchemy threaten your position on science? If not, why not accept it?

Simple, because the evidence disproves it. Unlike you I'm open minded enough to go where the evidence leads. You should try it.

 

[Bradskii]

Thanks for the summary. I appreciate it. Of course, a summary can't cover everything. It is, after all, a summary. So, I'm not faulting the book, or you for your summary. I will simply note that direct physical evidence of LUCA wasn't covered in your post. My wording in post #33 may also have been lacking. In that post I only said 'direct evidence' rather than 'direct physical evidence', which is what I meant.

I think that you're missing the point.

I have a family line that goes back literally for ever. My father had a father. Obviously. And his father had a father. And we can take that line back as far as you want. So we can deduce that there is a direct paternal line between someone who lived a million years ago and me. Who that was, where he lived, what he looked like...we have no idea, although we could make some educated guesses.

Now there are, almost certainly (but not definitely) some people alive today who share a direct paternal line from that ancestor. So he would be the last common ancestor.

Now if we propose that life only arose only started once, then all life would originate from that point. From that unicellular organism. And we could go back until we found a common ancestor (the CA of luCA) who was the last universal ancestor (the LU of LUca).

If life only arose once then the existence of a single LUCA is a logical necessity.

 

[Bradskii]

Does alchemy threaten your position on science? If not, why not accept it?

I'd say that it does, because it contradicts accepted science. The two aren't compatible. So I'd have to reject it. The corollary of that is to say that evolution and the existence of LUCA does not contradict a belief in God. So you wouldn't have to reject one to accept the other.

 

[J_B_]

I think that you're missing the point.

I have a family line that goes back literally for ever. My father had a father. Obviously. And his father had a father. And we can take that line back as far as you want. So we can deduce that there is a direct paternal line between someone who lived a million years ago and me. Who that was, where he lived, what he looked like...we have no idea, although we could make some educated guesses.

Now there are, almost certainly (but not definitely) some people alive today who share a direct paternal line from that ancestor. So he would be the last common ancestor.

Yes, I get the argument. It's all fine until the ancestral line passes out of our realm of knowledge. From there it's speculation. Within engineering, good practice is not to extrapolate. Extrapolation is, at best, a hypothesis. If the hypothesis is promising, then you are tasked with getting the necessary data to demonstrate it. If the necessary data is below the noise floor ... too bad. Move on. My understanding is that such practice is common to all the sciences as well.

Why does there have to be a beginning? Maybe the ancestral line is infinite. I wouldn't argue such a thing, but it is an alternative. It's also OK to say, "We don't know."

Now if we propose that life only arose only started once ...

Exactly. If biologists want to make LUCA a postulate, fine. The problem seems to be, though, that such would allow others to propose other postulates (as in Euclidean vs Hyperbolic geometry). That makes biology untidy. We have all these branches on the tree that don't connect ... except beyond the noise floor where LUCA lives. It's like leaving your left flank unprotected ... and with all those religious nutters out there, well, we just can't have that.

I'm absolutely convinced biologists could come up with a scientifically grounded alternative to LUCA that would not require invoking God. But what motivation is there to do that?

Again, as I understand it, biologists don't think life started only once. Another conversation of mine from the past:

Biologist (paraphrasing): If the conditions were right at time X for life to start, I would be shocked if the result wasn't life starting thousands of times during time period X.
J_B_: Cool! (hope rising)
Biologist: But of course, only one of those thousands of biogenesis events survived.
J_B_: Oh. (deflating)
Biologist: Obviously.
J_B_: Uh huh. Obviously.

 

[J_B_]

I'd say that it does, because it contradicts accepted science. The two aren't compatible. So I'd have to reject it. The corollary of that is to say that evolution and the existence of LUCA does not contradict a belief in God. So you wouldn't have to reject one to accept the other.

Ugh. In my mind I played with several examples, and landed on alchemy even though I knew it had its flaws. I guess the example was just so bad that you weren't able to look past it and surmise my point. Sometimes it is possible to see the point despite a bad example. I shouldn't do this when I'm tired. This is the result.

So, my point may be a dead horse, but I'll give it one more whack before I give up and retire for the night.

How about this: Does the fact that the 2020 election was stolen shake your faith in science? If not, then just accept it. (Note: I'm not MAGA, and don't believe 2020 was stolen, It's just an example.)

So, straight up. My point is this. Just because Unsupported Position A doesn't impact Position B, is NOT a reason to accept Position A. Why would I do something like that? Does that count as a false dichotomy? I'm not sure. Again, I'm tired. Good night.

 

[Bradskii]

Yes, I get the argument. It's all fine until the ancestral line passes out of our realm of knowledge. From there it's speculation.

No. If life started once, then it's a logical extrapolation that there's only one LUCA.

Why does there have to be a beginning? Maybe the ancestral line is infinite.

What? How on earth (literally) can it be infinite? It must have started here at some point. Again, that a logical necessity. Saying that it could be infinite is pure nonsense.

Exactly. If biologists want to make LUCA a postulate, fine. The problem seems to be, though, that such would allow others to propose other postulates (as in Euclidean vs Hyperbolic geometry). That makes biology untidy. We have all these branches on the tree that don't connect ...

There is no evidence that they don't. So based on our understanding of the evolutionary process, a LUCA is logically necessary.

I'm absolutely convinced biologists could come up with a scientifically grounded alternative to LUCA that would not require invoking God. But what motivation is there to do that?

That's exactly equivalent to saying that there's an alternative to me having a great great x one million grandfather. It's logically impossible. If life only started once then it's literally and logically impossible for there not to be a LUCA.

 

[Bradskii]

How about this: Does the fact that the 2020 election was stolen shake your faith in science? If not, then just accept it. (Note: I'm not MAGA, and don't believe 2020 was stolen, It's just an example.)

That's just as useless as the last example. Would your belief that sending me a thousand dollars will make you extremely rich shake your faith in science? No? Well, just send me the money.